The present invention is directed to facilitating air flow through the nasal passages of a domestic animal. Specifically, the invention provides devices and methods for supporting the soft tissue structures of the nasal passages of a domestic animal.
Portions of the following discussion of the nasal anatomy of domestic mammals are excerpted from R. Nickel et al., The Viscera of Domestic Animals, (2nd revised ed.), Springer-Verlag, New York, Hiedelberg, Berlin (1979), pp. 211-221. This is an excellent text on the comparative visceral anatomy of domestic mammals. As used herein, the terms xe2x80x9cmammalxe2x80x9d and xe2x80x9canimalxe2x80x9d are used synonymously and refer to non-human mammals.
The nasal anatomy of domestic animals is considerably different than that of a human. Unlike the human nose that projects distinctly from the face, in domestic animals, the nose is incorporated into the face and forms the large dorsal and lateral areas rostral to the eyes. The nostrils in the apex of the nose are the entry to the respiratory system of domestic mammals. Once passing through the nostrils, inspired air moves into the nasal cavities and continues through the nasopharynx, larynx, trachea and lungs.
At the apical entrance to the nose the nostrils are partitioned by the nasal septum to divide the nasal cavity into right and left halves. The caudal portion of the septum is bony, while rostrally the septum consists of cartilage which becomes progressively more flexible toward the apex.
The wall of the nose consists of skin externally and a middle supporting layer of bone caudally and cartilage rostrally. The nasal cavity is lined by a mucous membrane. The rostral bones forming the wall of the nose include the nasal, maxillary and incisive bones. The free borders of the nasal and incisive bone provide attachment for the cartilages which support the nostrils. The supporting bones and cartilages of the nose are associated with the nasal muscles that regulate the size of the nostrils.
The dorsal and ventral lateral nasal cartilages are formed by the widening of the rostral part of the nasal septum along its dorsal and ventral margins. In the horse, the ventral lateral nasal cartilage is small and may be absent. In many domestic animals, there is no lateral support for the soft tissue over the rostral nasal passage caudal to the nostril.
A further difference in the formation of the nasal cartilages of the horse is the presence of alar cartilages. The alar cartilages consist of a ventral cornu and a dorsal lamina and support the nostrils dorsally, medially and ventrally. The lamina of the alar cartilage and the medial accessory cartilage support the nasal diverticulum, a blind pouch in the dorsal aspect of the nostril.
The muscles of the nose and upper lip act to dilate the nostrils. This is particularly noticeable during labored breathing. In the horse, these muscles are well developed and can transform the normally semilunar nostrils to become circular.
The dorsal lateral area of the rostral nasal cavity that is caudal to the alar cartilages in the nostrils of the horse includes a region of unsupported soft tissue which can be drawn into the nasal cavity during inspiration of air into the nasal passages. The nasal diverticulum of the horse is a part of the soft tissue structures of the horse which can be drawn into the nasal cavity. When the soft tissue is drawn in, it can narrow the nasal cavity and reduce the area for the intake of air, thus reducing the air movement into the nasal passages and ultimately to the lungs where the oxygen is transferred in the pulmonary aveoli. The physiological effects of reduced oxygen transfer at rest and during physical exertion are documented. Some experts have theorized that exercise induced pulmonary hemorrhage (EIPH) in performance horses is caused by asphyxia due to abnormal resistance of a closed or partially closed upper airway. The upper airway being defined as the region of the respiratory tract lying between the nostrils and the windpipe at the level of the first rib. Hence, the nasal passages are part of this region. Dr. Robert Cook, xe2x80x9cEIPH or AIPE? A Tufts University Researcher suggests that bleeding is not caused by EIPH, but by asphyxiaxe2x80x9d, The Equine Athlete, p. 22-23 (March/April 1997).
Devices for dilating the outer wall tissue of the nasal passages in humans have been described in, for example, U.S. Pat. Nos. 5,533,503; 5,546,929; 5,553,605; and RE 35,408. These devices, however, do not address the unique soft tissue structures and mechanical problems associated with providing support for the nasal tissues of non-human mammals, especially large performance mammals such as the horse and camel.
Accordingly, there is a need to reduce the detrimental effects of reduced air intake, or to enhance the physiological benefit of increased air intake, during physical exertion of domestic mammals. Specifically, there is a need to increase, or reduce the decrease of, nasal passage narrowing that can occur during breathing in domestic mammals, especially performance animals such as the horse, camel, and dog.
The present invention provides devices and methods for using the devices to support the unsupported nasal tissues of a domestic animal. The invention addresses providing support in view of the structural and physiological characteristics unique to the nose of a non-human animal, for example, a horse. In some embodiments, a nasal support device (NSD) disclosed herein can reduce inspiratory air flow impedance by at least about 5-10%
In one embodiment the invention is a NSD for securing to the nose of a domestic animal. The NSD provides support to the right and left lateral vestibular walls of a domestic animal. The device includes a support layer and a right and left side piece which when secured to the nose of the animal are positioned to provide structural support to the right and left lateral vestibular walls. The side pieces of the device can meet at the midline region of the device. When secured to the nose of a domestic animal, the midline region of an NSD of the invention straddles the left and right nasal bones of the animal.
The sides and the midline region of the NSD each have a rostral end, a caudal end and a rostral-poll dimension. In one embodiment, the rostral-poll dimension of the midline region is at least as great as either of the rostral-poll dimensions of the side pieces. In an alternative embodiment, the rostral-poll dimension of the midline region is greater than either of the rostral-poll dimensions of the side pieces. In some embodiments, the rostral-poll dimension at the midline region is greater than either of the rostral-poll of the side pieces and the device is bilaterally symmetrical across both the longitudinal and transverse axes of the device. In some embodiments, the rostral end of the NSD can extend rostrally between the nostrils in the form of a xe2x80x9ctonguexe2x80x9d to provide externalizing support to the soft tissues between the nostrils.
An NSD configured according the invention can be used on many different animals. In one embodiment an NSD is sized to fit a member of the Equidae family, including the domestic horse. The device is suitable for adults and young animals. In general, the structural aspects of an NSD of the invention can be configured and sized to fit the nose of, for example, a dog, human, horse, camel, etc.
In general, an NSD comprises a support layer, an engaging layer, and in some embodiments a surface layer and/or pad layer. The support layer of an NSD can include one or more lift members to support the vestibular wall. The lift members can traverse the nose and extend to a point dorsal to the ventral border of the vestibular wall, or beyond the ventral border of the vestibular wall lateral to the incisive bone. Alternatively, one or more lift members of an NSD can be applied over each vestibular wall and act to externally stent each vestibular wall independently without connecting to one another across the midline of the nose.
The invention further provides a method for supporting a first and second vestibular free wall of a domestic animal by securing a device which supports the first and second vestibular free walls to the nose of the animal. In one embodiment, the method includes use of an NSD as disclosed herein.
The method of the invention provides for facilitating air flow through the nasal passages of a domestic animal. The device and method of the invention are particularly advantageous for use in the horse and are beneficial for facilitating athletic performance or for reducing the occurrence, severity or affect(s) of respiratory diseases in an adult or young animal.
A device and method according to the invention can he used on an animal that is running freely in a pasture, or wearing saddlery, harnesses or other equipment that can be attached to the nose of the animal.